The U.S. Supreme Court on Monday declined an appeal to examine Obama-era net neutrality rules that had been cheered by open internet advocates.

Several major internet providers sought to throw out a 2016 ruling by the U.S. Court of Appeals for the D.C. Circuit in favor of net neutrality rules that require internet service providers to offer equal access to all web content.

Those rules were put in place by the Federal Communications Commission under President Barack Obama, but have since been rolled back under the administration of President Donald Trump.

The Supreme Court's decision leaves in place the previous Circuit Court ruling that found the FCC acted legally in passing its net neutrality rules.

Gigi Sohn, a former lawyer at the FCC who is now a fellow at the Georgetown Law Institute for Technology, Law and Policy, said the ruling was significant because the Circuit Court ruling helped form the basis of a variety of legal challenges leveled at the FCC's repeal of the rules.

"The FCC and industry had argued that because the Trump FCC has repealed the 2015 rules, the 2016 decision was moot, and the Supreme Court should wipe it from the books," Sohn said in an email. "Now that the Supreme Court has refused to do so, parties challenging the 2017 net neutrality repeal order can continue to rely on that 2016 decision, which provides strong support for their argument that the 2017 repeal is contrary to law."

Jessica Rosenworcel, the lone Democratic FCC Commissioner who has been a vocal advocate of net neutrality rules,‏ tweeted Monday that the decision was "interesting."

It wasn't enough for this @FCC to roll back #NetNeutrality. It actually petitioned the Supreme Court to erase history and wipe out an earlier court decision upholding open internet policies. But today the Supreme Court refused to do so.

FCC Chairman Ajit Pai called the previous regulations "micromanaging" of the internet.

Under the current rules, the Federal Trade Commission is tasked with policing how internet service providers handle web traffic in order to prevent "anti-competitive" behavior. Critics of the law believe this opens the door for service providers to charge additional fees or censor certain content.

Justice Brett Kavanaugh took no part in Monday's ruling because the appeal had come from his former court. Conservative Justices Clarence Thomas, Samuel Alito and Neil Gorsuch said they would vacate the lower court decision.

Sen. Ed Markey, D-Mass., said the ruling marked an important win for net neutrality advocates.

"“The FCC’s Open Internet Order is regarded as settled law by the courts, and that is what today’s decision by the Supreme Court really means," Markey said in an emailed statement. "This is an important win for the internet and all Americans who support strong net neutrality rules."

Pete Williams

Pete Williams is an NBC News correspondent who covers the Justice Department and the Supreme Court, based in Washington.